If they both collide, they do.
Your buff example is actually the most legit example, because the buff doesn't have much chance to maneuver versus an incoming fighter.
Both fighter pilots are in control of their plane. They can easily move the controls to avoid the other plane. If they don't, that's on them. If it's happening to you on a regular basis, consider moving out of the way, and be happy that if you successfully see yourself avoid the other plane, you won't take damage if he collides, unlike what you're proposing.
Wiley.